Ethernet is one of the most widely-installed Local Area Network (LAN) technologies. Users are attracted by a number of advantages of Ethernet services, including ease of use, cost effectiveness, flexibility, and wide rage of service options. Ethernet services have been extended throughout metropolitan areas and beyond.
Ethernet services may vary in many ways. The Metropolitan Ethernet Forum (MEF) defines two types of Ethernet services: E-Line services, which are point-to-point services; and E-LAN services, which are multipoint services. MEF specifies distinct layer-1 and layer-2 E-LAN services. A layer-1 E-LAN service is called an Ethernet LAN (ELAN) service, and a layer-2 E-LAN service is called an Ethernet Virtual LAN (EVLAN) service. The EVLAN allows users to exchange frames as if connected to a shared medium LAN.
Two methods currently used to specify rate guarantees for EVLAN services are port-to-port guarantee and per-port guarantee. Port-to-port guarantee specifies a distinct bandwidth guaranteed for traffic from a specific port to another specific port. This is a traditional guarantee provided in frame relay and private-line services. This method may be more efficient when port-to-port traffic rate is relatively constant.
Per-port guarantee specifies distinct bandwidth guaranteed for traffic originating from each port, without regard to destination ports. This type of guarantee is relatively easy to police as only knowledge of local port ingress traffic is required. A service provider needs to, however, support a case in which every user is sending at a full ingress rate.
A technology known as an Ethernet Bus (or Carrier Sense Multiple Access/Collision Detection—CSMA/CD, or Shared Medium Ethernet) provides services similar to an aggregate-rate guarantee. An Ethernet Bus has the ability to share the capacity of a network among user ports, with some inefficiency introduced by methods of mediation among the ports. However, the Ethernet Bus may not be applied to networks of arbitrary technology, and the specified aggregate-rate may not have an arbitrary value.
U.S. patent application No. 20030165146 describes how the capacity of a network having a ring topology may be shared among users, such that each instance of service appears to its users as a private network, whose capacity is shared fairly among its users. However, this method is not applicable to a network of an arbitrary topology.
The IEEE P802.1ad Draft Standard for Local and Metropolitan Area Networks—Virtual Bridged Local Area Networks—Amendment 4: Provider Bridges, describes how a network of arbitrary topology may be partitioned into distinct instances of a Service Virtual LAN (SVLAN). However, the method of IEEE P802.1ad does not explicitly support aggregate-rate services or fair sharing of network capacity among members of a group of users.
The IEEE P802.17 Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 17: Resilient Packet Ring (RPR) access method and physical layer specifications, describes how the capacity of a network having a ring topology may be shared fairly among its users. However, the method of IEEE P802.17 only supports the fair sharing of capacity in a network having a ring topology, and is not applicable for a network of arbitrary topology.
The Metropolitan Ethernet Forum—Technical Specification D00044—004 Ethernet Services Attributes—Phase 2—Approved Draft 4, 14 Nov. 2005, describes how capacity may be associated with a user port, or with a virtual connection between or among user ports. However, the Metro Ethernet Forum method does not explicitly support aggregate-rate services or fair sharing of capacity among members of a group of user ports associated with a virtual connection.
Therefore, there is a need for a system that provides flexible and cost effective rate guarantee services in a communications network; an aggregate-rate guarantee, with sharing of aggregate capacity fairly among members of a group of customer ports, and applicable to a network of an arbitrary topology; aggregate-rate services that accommodate bursty network traffic in an efficient and cost effective manner.